Search

The paper presents experimental findings on the atomization characteristics of coal–water slurries with and without petrochemicals. The fuels were based on flame coal filter cake (slime), which is a typical coal processing waste, flame coal of different particle sizes, wood biomass (sawdust), used transformer oil, and water. The atomized flow characteristics—droplet size and velocity as well as jet angle—were found to depend on the atomizer dimensions and slurry rheology. The experimental data were used to calculate the slurry atomization efficiency factor. The findings were generalized to provide a mathematical description of how the slurry composition and atomizer geometry affect the slurry atomization behavior. Approximations were obtained for atomization characteristics that can be used to predict the jet angle as well as droplet radii and velocities. The developed mathematical tool can be employed to calculate the spraying characteristics when using devices like external-mix twin-fluid atomizers. The approach proposed for data generalization can be applied to adapt the set of approximation equations to other types of nozzles. [ABSTRACT FROM AUTHOR]

It is not possible to imagine the implementation of investment and construction projects for industrial purposes in isolation from the environment. During the construction and further operation of enterprises, it is necessary to remember the close relationship between nature and man and plan the processes of waste disposal from harmful substances. In pursuit of profit, management often forgets about air and water purification measures, which causes deterioration of the natural environment around the enterprise, complaints from residents, loss of business reputation, and often financial losses due to the need to eliminate the consequences of emissions. Thus, during the construction of industrial facilities, an important task is not only the calculation of profits from operation, but also environmental protection measures, which must necessarily be carried out by enterprises. The growth of the country's economy largely depends on the growth of gross domestic product (GDP). In 1934, when this indicator was first introduced, it was most often used to understand how much the country is ready for hostilities and how many products enterprises can produce to ensure stable functioning. Later, in the 40s, the indicator was associated with the volume of industrial production, since the service sector at that time was poorly developed. And accordingly, the calculation of the GDP indicator was a very necessary mechanism: the growth of GDP per capita from one thousand to 10 thousand. dollars meant a rapid leap in the material well-being of the population.

Experimental research findings are reported on the characteristics of surface transformation of droplets of promising fuel slurries in the air, as they move at subsonic velocities typical of combustion chambers of power plants. The main components of the fuels were water, coal processing waste, and coal. Typical shapes of droplets and the duration of their deformation cycles were identified. Droplets containing more than 70% of the solid phase remained practically undeformed. The lowest relative velocities of droplets leading to their fragmentation were determined. The key characteristics of secondary droplets (their number, sizes, velocities, and surface area of liquid) were calculated on the basis of the experimental findings. These characteristics were compared with those of initial droplets. Disruption conditions in the chosen range of the gas jet pressure (P ≤ 6 bars) can only be provided for fuel slurry droplets containing less than 60% of a coal component. The effect of a group of factors on deformation characteristics was identified. These include air jet and droplet velocities, droplet sizes, temperature, concentration, and type of components and additives. Approximation equations were derived for the mathematical description of the experimental data. Using certain criteria, the conditions necessary and sufficient for the disruption of water–fuel slurries on impact with an air jet were estimated. [ABSTRACT FROM AUTHOR]

The effect of coal hydrophilic particles in water-glycerol drops on the maximum diameter of spreading along a hydrophobic solid surface is experimentally studied by analyzing the velocity of internal flows by Particle Image Velocimetry (PIV). The grinding fineness of coal particles was 45–80 μm and 120–140 μm. Their concentration was 0.06 wt.% and 1 wt.%. The impact of particle-laden drops on a solid surface occurred at Weber numbers (We) from 30 to 120. It revealed the interrelated influence of We and the concentration of coal particles on changes in the maximum absolute velocity of internal flows in a drop within the kinetic and spreading phases of the drop-wall impact. It is explored the behavior of internal convective flows in the longitudinal section of a drop parallel to the plane of the solid wall. The kinetic energy of the translational motion of coal particles in a spreading drop compensates for the energy expended by the drop on sliding friction along the wall. At We = 120, the inertia-driven spreading of the particle-laden drop is mainly determined by the dynamics of the deformable Taylor rim. An increase in We contributes to more noticeable differences in the convection velocities in spreading drops. When the drop spreading diameter rises at the maximum velocity of internal flows, a growth of the maximum spreading diameter occurs. The presence of coal particles causes a general tendency to reduce drop spreading. [ABSTRACT FROM AUTHOR]

This paper presents experimental research into the propagation of a liquid fuel combustion front interacting with a fire barrier made of CO2 hydrate and ice. The combustible liquids studied here were kerosene, gasoline, Diesel fuel, oil, petroleum, and alcohol. The experiments with gas hydrate involved fire barriers based on powder and tablets. Heat and mass transfer and phase transitions in the area between the fire barrier and the combustion front were found to play a fundamental role. The liquid fuel combustion fronts propagate at a velocity ranging from 0.1 m/s to 3 m/s under natural convection. Forced convection leads to 2- to 5-fold changes in the flame propagation velocities. According to our experiments, 2–4 cm is the minimum width of a CO2 hydrate fire barrier for stopping the flame combustion front. We also determined the contribution of the gas hydrate dissociation to fire suppression and identified the conditions of the combustion front stoppage. The dimensionless processing of experimental data made them scalable to industrial applications. Finally, the experimental findings were also used to develop physical and mathematical models predicting the necessary and sufficient amount of CO2 hydrate in a fire barrier to provide the effective deceleration and stoppage of a flame combustion front. [ABSTRACT FROM AUTHOR]

This paper presents the experimental findings on fire containment and suppression by dropping CO2 hydrate granules and tablets on burning solid materials. We used the combustible materials typical of compartment fires—wood, linoleum, and cardboard—to determine the volume and mass of gas hydrate powder necessary for the effective fire suppression. Gaseous emissions were recorded from the combustion with and without fire suppression using hydrates. Conditions were specified in which a fire can be extinguished with minimum air pollution. We also identified the conditions for effective fire containment and suppression using hydrates as compared to water spray, snow, and ice. The necessary volume of hydrate was determined for effective fire suppression in a compartment filled with various materials. Experimental data show that the impact of temperature on the CO2 hydrate decomposition is highly nonlinear. The carbon dioxide hydrate exhibited a much better fire suppression performance than water spray in the course of total flooding of solid combustible materials. It was established that fine water spray failed to reach the lower levels of multi-tier crib fires. Finally, key patterns of total flooding with CO2 hydrate powder were identified when applied to fires. [ABSTRACT FROM AUTHOR]